Heater switch problem

[bishgt]

1994 nissian sentra Le 1.6 litre engine 209.000 milesMay someone please help me,the heater switch will not Work on none off the speeds .if you move the control lever that switches the inside air to outside it would Work now you have to move it back three or four time before it come on. does anyone have any ideal what It may be. i also i replace the heater resitor last year.